This invention relates to improvements for battery strap and post cast-on machines of the type disclosed in U.S. Pat. Nos. 3,718,174 and 3,802,488 respectively issued Feb. 27, 1973, and Apr. 9, 1974, both of which issued to Donald R. Hull and Robert D. Simonton. In those machines, stacked battery plates and separators for a plurality of cells making up a lead-acid storage battery have the respective connection lugs on the positive and negative plates of each cell interconnected by a cast-on strap and an intercell connecting post or terminal post cast as an integral portion of each strap. These casting operations are accomplished simultaneously with the cells inverted but otherwise oriented as they are to be in the finished battery structure. Stacked cell elements are clamped with the plate lugs extending downward. A plurality of properly oriented mold cavities are preheated as by directing a gas flame over them. Molten metal, usually containing a large proportion of lead, is circulated continuously along a channel next to the cavities and the flame which is reducing also preconditions the upper surface of the metal. When desired conditions are achieved, the molten metal level is raised to overflow wiers between the channel and each mold cavity to fill the cavities, the molten metal is then permitted to recede, the flame is removed, and the clamped cell assemblies are positioned to immerse a portion of the plate connecting lug on each plate in the molten mass in an appropriate connector strap cavity. The cavities are then chilled, as by flowing water through the body of the mold, and when the molded straps and posts solidify adequately they are extracted from the mold with the plates fused thereto.
A procedure as outlined above should be accomplished in repetitive cycles for efficient commercial utilization. Cycle time should be reduced to a minimum. It has been found that a substantial portion of the cycle time is involved in the heating and cooling of the mold body. Further, where the molten metal flow channels are in the mold assembly, the channel walls should not be chilled to such a degree that the metal flow is impeded during the freezing of the straps and posts. This required some degree of precision in the temperature control of the mold assembly. It has been found desirable to cool the posts, particularly the terminal posts, at least as rapidly as the less massive straps since the slower cooling of the posts tends to result in mechanically weak terminals. Accordingly, greater control of localized temperature in the mold assembly than has been available heretofore is desirable.
Mold expense is a significant factor in machines of the type under consideration. It has been difficult to obtain suitable castings in which mold forms can be produced. The variety of cell and terminal arrangements required for lead-acid batteries has further complicated mold construction.
In accordance with the above, an object of this invention is to improve mold assemblies for battery strap and post cast-on machines.
A second object is to decrease cycle time of battery strap and post cast-on machines.
A third object is to reduce the cost of mold assemblies.
A fourth object is to increase the control of localized thermal conditions in mold assemblies.